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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-04-01 11:20:36 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-04-29 08:45:19 -0700 |
| commit | 5057f55e543b7859cfd26bc281291795eac93f8a (patch) | |
| tree | 37cf522d549037e6e31d57159d8ab7668e085715 /kernel/rcu | |
| parent | rcu: Document RCU_INIT_POINTER()'s lack of ordering guarantees (diff) | |
| download | linux-dev-5057f55e543b7859cfd26bc281291795eac93f8a.tar.xz linux-dev-5057f55e543b7859cfd26bc281291795eac93f8a.zip | |
rcu: Bind RCU grace-period kthreads if NO_HZ_FULL
Currently, RCU binds the grace-period kthreads to the timekeeping
CPU only if CONFIG_NO_HZ_FULL_SYSIDLE=y. This means that these
kthreads must be bound manually when CONFIG_NO_HZ_FULL_SYSIDLE=n and
CONFIG_NO_HZ_FULL=y: Otherwise, these kthreads will induce OS jitter on
random CPUs. Given that we are trying to reduce the amount of manual
tweaking required to make CONFIG_NO_HZ_FULL=y work nicely, this commit
makes this binding happen when CONFIG_NO_HZ_FULL=y, even in cases where
CONFIG_NO_HZ_FULL_SYSIDLE=n.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 34 |
1 files changed, 16 insertions, 18 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 1af19e006899..045c6d04ed3f 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2596,20 +2596,6 @@ static bool is_sysidle_rcu_state(struct rcu_state *rsp) } /* - * Bind the grace-period kthread for the sysidle flavor of RCU to the - * timekeeping CPU. - */ -static void rcu_bind_gp_kthread(void) -{ - int cpu = ACCESS_ONCE(tick_do_timer_cpu); - - if (cpu < 0 || cpu >= nr_cpu_ids) - return; - if (raw_smp_processor_id() != cpu) - set_cpus_allowed_ptr(current, cpumask_of(cpu)); -} - -/* * Return a delay in jiffies based on the number of CPUs, rcu_node * leaf fanout, and jiffies tick rate. The idea is to allow larger * systems more time to transition to full-idle state in order to @@ -2819,10 +2805,6 @@ static bool is_sysidle_rcu_state(struct rcu_state *rsp) return false; } -static void rcu_bind_gp_kthread(void) -{ -} - static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, unsigned long maxj) { @@ -2853,3 +2835,19 @@ static bool rcu_nohz_full_cpu(struct rcu_state *rsp) #endif /* #ifdef CONFIG_NO_HZ_FULL */ return 0; } + +/* + * Bind the grace-period kthread for the sysidle flavor of RCU to the + * timekeeping CPU. + */ +static void rcu_bind_gp_kthread(void) +{ +#ifdef CONFIG_NO_HZ_FULL + int cpu = ACCESS_ONCE(tick_do_timer_cpu); + + if (cpu < 0 || cpu >= nr_cpu_ids) + return; + if (raw_smp_processor_id() != cpu) + set_cpus_allowed_ptr(current, cpumask_of(cpu)); +#endif /* #ifdef CONFIG_NO_HZ_FULL */ +} |